This invention relates to a resin that is intended particularly for the fabrication of oriented-reinforcement prepregs that is suitable for shaping with oriented-reinforcement materials and to their applications in the areas of leisure activities; shipbuilding, aviation, and automotive design; and the electrical and electronics industries.
Prepregs made of unsaturated polyester resin in the form of relatively rigid sheets with a thickness of up to about 1 cm, particularly for the production of large-dimension parts with good mechanical resistance, are already known. They are obtained by impregnating long glass fibers (i.e., of a length at least equal to about 25 mm) by a paste of low viscosity that comprises unsaturated polyester resin, a free-radical catalyst, a shrinkage-compensating agent, a curing agent (such as magnesia), a demolding agent, an ethylenically unsaturated monomer, a mineral filler, and, if necessary, a pigment paste, then by allowing the viscosity to increase during a so-called curing phase.
Furthermore, various polyester-polyurethane hybrid resins are known, particularly from patents U.S. Pat. No. 4,107,101; U.S. Pat. No. 4,280,979; U.S. Pat. No. 4,880,872; FR-A-2 667 602 and WO 94/00503.
For the needs of various applications in the areas of leisure activities; shipbuilding, aviation, and automotive design; and the electrical and electronics industries (particularly for printed circuits), attempts are now being made to find oriented-reinforcement prepregs that simultaneously have a set of favorable properties such as:
good wetting of the oriented reinforcement (such as glass, carbon or organic fiber, cloth or mat) by the synthetic resin, PA1 manipulability of the prepreg (i.e., sufficient rigidity and absence of sticking) after as short a time as possible, PA1 stability of the prepreg (i.e., moldability), after storage at a temperature of about -18.degree. C. to 30.degree. C., for as long a period as possible, PA1 as low a molding temperature and as short a molding time as possible, PA1 good adhesion of the prepreg to materials as varied as metals (in particular copper, steel and aluminum), thermoplastic polymers (such as particularly polyethylene, polypropylene, polyamides), and polyurethanes (in the form of, for example, foam), PA1 mechanical properties (particularly tensile strength, flexural strength, compression strength and impact resistance, elastic limit) that are as high as possible both at room temperature (up to about 40.degree. C.) and under cold conditions (to about-40.degree. C.). PA1 a first component that comprises (A) at least one polyisocyanate that has a functionality of 2 to 3, i.e., contains 2-3 NCO groups, and (B) a peroxide or a peroxide mixture that is able to initiate polymerization by free radicals at a ratio such that: ##EQU1## is about 0.5 to 4% by weight, with a second component that comprises: PA1 tertiary amines such as bis(dimethylaminoethyl)ether, trimethylamine, triethylamine, N-methylmorpholine, N-ethylmorpholine, N,N-dimethylbenzylamine, N,N-dimethylethanolamine, N,N,N',N'-tetramethyl-1,3-butanediamine, triethanolamine, 1,4-diazabicyclo[2,2,2] octane and pyridine oxide, PA1 tertiary phosphines such as trialkylphosphines and dialkylbenzylphosphines, PA1 strong bases such as hydroxides, alcoholates and phenolates of alkaline and alkaline-earth metals, PA1 metallic salts of strong acids such as ferric chlorides, stannic chlorides, stannous chlorides and bismuth chlorides, antimony trichloride and bismuth nitrate, PA1 chelates such as those that can be obtained from acetylacetone, benzoylacetone, trifluoroacetylacetone, ethyl acetoacetate, salicylaldehyde, cyclopentanone-2-carboxylate, acetylacetoimine, bis-acetylacetonealkylene diimines, salicylaldehyde imine and starting from metals such as beryllium, magnesium, zinc, cadmium, lead, titanium, zirconium, tin, arsenic, bismuth, chromium, molybdenum, manganese, iron, cobalt and nickel, PA1 alcoholates and phenolates of metals such as Ti(OR).sub.4, Sn(OR).sub.4, Sn(OR).sub.2 and Al(OR).sub.3 in which R is an alkyl or aryl group, PA1 salts of organic acids and metals such as alkaline. metals and alkaline-earth metals, aluminum, tin, lead, manganese, cobalt, nickel and copper, for example, sodium acetate, potassium laurate, calcium hexanoate, stannous acetate, stannous octoate and stannous oleate, lead octoate, manganese and cobalt naphthenates, and PA1 carbonyl metals of iron and of cobalt and organometallic derivatives of tetravalent tin, of trivalent and pentavalent arsenic, of antimony and bismuth; among these derivatives more particular preference is given to dialkyltin salts of carboxylic acids such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, dilauryltin diacetate, dioctyltin diacetate, dibutyltin bis(4-methylaminobenzoate), dibutyltin (6-methylaminocaproate), trialkyltin hydroxides, dialkyltin oxides, dialkyltin dialkoxides and dialkyl tin dichlorides.
As far as the synthetic resin that impregnates the oriented reinforcement is concerned, these different requirements are expressed by the need for a pot service life ("pot life") at room temperature (23.degree. C.), or stability before use, of at least about 30 minutes and preferably at least about 45 minutes to carry out the impregnation of the oriented reinforcement.
In addition, in the fabrication of certain high-performance products that are intended for areas of leisure activities; of shipbuilding, aviation, and automotive design; and of the electrical and electronics industries, whereby the high performance levels of these products are attained by juxtaposing several (at times up to 5) materials of different types, including an oriented-reinforcement material that is preimpregnated with resin, a process of production that consists in assembling the various materials--with the exception of the resin--in a mold, then injecting the resin into the mold while molding the product by raising the temperature of the mold until the resin hardens enough to connect the oriented reinforcements and to ensure the adhesion of the oriented-reinforcement material to the other constituent materials of the product are known. This process makes it possible to guarantee the high performance levels of the products thus obtained, particularly high mechanical properties at room temperature and under cold conditions. It has the drawback, however, of requiring a relatively long molding time, for example, on the order of 20 minutes around 100.degree. C. (case of the electronics industry) or else a cycle of several hours for increasing the molding temperature from 120.degree. to 180.degree. C. (case of the automotive industry). This drawback interferes with the productivity of the manufacture of these products and consequently accounts for their high costs. For the needs of high-performance products intended for the areas of leisure activities; shipbuilding, aviation, and automotive design; and the electrical and electronics industries, whereby the high performance levels of these products are attained by juxtaposing several (at times up to 5) materials of different natures, including a preimpregnated oriented-reinforcement resin material, researchers are therefore searching for a production process that makes it possible to maintain the high performance levels while significantly shortening the molding times of the materials. The possibility of attaining this object of the process depends quite obviously on the number and the nature of the constituent materials of these products, but primarily on the ability to find a resin that provides all of the properties listed above and is able particularly to harden (crosslink) during a molding process in a very short period of time.